The present invention pertains to a process and apparatus for precisely and rapidly mixing base solutions. More particularly, it pertains to such a process and apparatus especially useful for the compounding of hyperalimentation solutions.
Hyperalimentation therapy is the intravenous feeding of, for example, a protein-carbohydrate mixture to a patient. It is used primarily to meet the patient's protein and caloric requirements which are unable to be satisfied by oral feeding. The protein may be in the form of free-amino acids or protein hydrolysate and the carbohydrate commonly is dextrose. In addition to the protein and carbohydrate, vitamins (water-soluble and fat-soluble) and electrolytes also can be supplied in this therapy.
Each of these parenteral ingredients and the combination thereof are particularly susceptible to the growth of deleterious organisms and it is desirable that they be administered to the patient in a sterile condition. Thus, because these protein and carbohydrate solutions cannot be pre-compounded by the manufacturer, but must be combined at the time of their use, their compounding must be performed under sterile conditions to avoid organism growth.
A known apparatus and process for compounding hyperalimentation solutions utilizes a solution transfer system including a receiving container and a Y-transfer set. The Y-transfer set includes two separate tubes, each having an end attached to a common juncture by which solutions delivered through the tubes will pass through the juncture into the receiving container. The other end of one tube of the set is attached to the protein holding container and of the other tube of the set to the carbohydrate holding container. The desired volume of each solution being transferred to the container is controlled by a clamp placed on each tube. The solutions may be allowed to flow into the receiving container by gravity flow. However, it has been found to be useful to transfer the solutions under the influence of a vacuum applied to the receiving container. When the receiving container is a flexible plastic container, the vacuum is created in a vacuum chamber into which the container is placed.
It has been known in the past that to ensure sterility during the compounding of hyperalimentation solutions, compounding should be performed under a laminar flow hood. Laminar flow hoods are used for reducing the risk of air-borne contamination of such solutions. These units operate by taking room air and passing it through a pre-filter to remove gross contaminates, such as dust and lint. The air is then compressed and channeled through a bacterial retentive filter in the hood in a laminar flow fashion. The purified air flows out over the entire work surface of the hood in parallel lines at a uniform velocity. The bacterial retentive type of filter is designed to remove all bacteria from the air being filtered.
Compounding under a laminar flow hood aids in preventing airborne contamination, but it is relatively cumbersome and expensive and would not be useful for eliminating any other source of contamination, such as contamination caused by handling. When using a hood the operator may inadvertently perform the work at the end or outside of the hood and not within the recommended space, at least six (6) inches within the hood, which insures the benefits of the air being purified. Time must be taken and care must be exercised to maintain a direct open path between the filter and the compounding area. Solution bottles and other non-sterile objects cannot be placed at the back of the hood work area next to the filter because these objects could contaminate everything downstream and disrupt the laminar flow pattern of the purified air. Also, in using a laminar flow hood, it is necessary routinely to clean the work surface of the hood before any compounding is performed.
Other manually controlled devices are known from the prior art for mixing base solutions. These devices use peristaltic pumps to transfer specified quantities of solution to transfer specified quantities of solution to a container. The desired quantities of solution to be transferred are determined in advance and entered by hand into the control unit of the pumping apparatus. The pumping apparatus them delivers the desired quantity of solutions to the mixture container. Such an apparatus and method are disclosed in U.S. patent application Ser. Nos. 391,758 and 391,759, both filed on June 24, 1982 and entitled respectively "Flow Monitoring Method and Apparatus" now U.S. Pat. No. 4,467,844 and "High Speed Bulk Compounder." Said applications have been assigned to the assignee of the present invention.
In order to use the devices and methods disclosed in the above identified applications it is usually necessary to manually translate a prescription from a short-hand designation to a set of parameters that includes the type, concentration and volume of each of the base solutions to be mixed. After the base solutions have been mixed, additives such as trace elements or vitamins can be added to make the final mixture.
The manual translation to a set of volumetric parameters is both time consuming and expensive as the process is usually carried out by a pharmacist. In addition, errors can occur during the calculation process. Further, the manual calculations to a certain extent are only approximations in that the small volumetric additions of the additives are often not taken into consideration.
If a group of prescriptions is to be compounded, once the manual translations have been completed, the order in which the members of the group are compounded becomes important. Compounders of the type disclosed in the above two applications are designed such that a container of base solution that has been partly emptied cannot be removed from the compounder and later reinserted. The containers of base solution which include dextrose, lipids and sterile water are expensive. It is therefore desirable to completely empty each container before removing it from the compounder.
To minimize over-all cost it would be desirable to optimize the compounding of a group of prescriptions by minimizing the needed number of containers of base solution. This requires a careful ordering of all prescriptions to be prepared at one time. Finally, labels must be prepared to identify each mixed prescription.
The process and method of the present invention provide for the translation from a prescription name to a detailed set of parameters without manual calculations. In addition, the compounding of a group of prescriptions can be optimized by the present invention by sorting the prescriptions in accordance with the type of base solution and then compounding them in the sorted order.